727 Reverse servo problem

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MR4V

MR4V

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I'm definatly no expert on atuo transmission so I'm a bit in the dark here.
Put a rebuilt 727 with reverse paten manual valve body, bolt in sprag, 4000 stall, from memory it has a 5.1 lever.
On the first start up I noticed it slipped in reverse so I re checked the fluid level and all was good.
Took it for a run and the box changes perfectly in all forward gears, nice and sharp, go's in to reverse perfect and on level ground rolls backwards put a bit of gas and it slips, if I try to back up a hill it justs slips and slowly go's backwards.
I have checked the cable on the shifter and all lines up spot on, running full mineral oil, trans cooler & deep pan, running temp is 150.
Dropped the pan and found the rear servo spring has pushed past the retaining clip, also found this metal disc in the pan.
Whats your opinion on what happened?


 
looks like the wrong servo spring(looks like a front servo spring), too heavy duty. you should be able to compress it be hand, with that one it isn't going to happen. also remove the spring on the inside of the piston and replace it with a spacer or washers. you need to place it in a vice for this operation.
 
There's also the guy that sells sweet billet setups on Moparts. comes with spring, etc.
 
I agree with Bob that the spring looks much heavier than you usually see on a reverse servo. And the reverse servo spring retainer clip is a weak spot so maybe the combination of the 2 caused it. I've used Mr. Randy's (the guy on Moparts) Billet reverse servo and spring setup. Works great. Much stronger than stock.

Can't tell for sure what the metal piece is but it kinda looks like a piece from the reverse band linkage has snapped off. Hope not cause if that's the case the trans. will need to come out and be disassembled to replace it. Inspect the rear band linkage real good.
 
bOb shingler said:
looks like the wrong servo spring(looks like a front servo spring), too heavy duty. you should be able to compress it be hand, with that one it isn't going to happen. also remove the spring on the inside of the piston and replace it with a spacer or washers. you need to place it in a vice for this operation.
Click to expand...

So I pulled the reverse servo piston & found a hair line crack in the piston. I have order the billet piston kit from EBay (couldn't find the one on Moparts) & should be here within the week.
I'm confussed about the spring as it was the one supplied with the manual valve body, also can someone upload a picture of the inside spring replaced with washers or a spacer.

Could the half piece that was in the pan be part of the govenor?

Thanks
 
that spring being supplied with the valve body i'd say it goes in the front servo for sure. the front servo needs a strong spring to unclamp the drum. in a trans fluid pressure clamps and spring pressure releases. that be said a strong spring is needed in the front because it needs to release fast and no so for the rear servo.
 
I have a post here that you might be interested in reading through:
http://www.forabodiesonly.com/mopar/showthread.php?t=245164

In the mean time here is a pic of the stock L/R servo
revserv_zps2a030889.jpg


And here are a few with the transgo upgrades

tf2springandbush_zps9db33cc3.jpg


and Billet servo and blocking spacer.

tsrlorev_zps1ad03523.jpg


tsrlorev2_zpsf6bb3945.jpg


As fishy said.. I would definitely give the trans a thorough inspection.

I hope this helps

-AlV
 
MR4V said:
Could the half piece that was in the pan be part of the govenor?

Thanks
Click to expand...

No, it's way more likely that it is part of the strut assembly for the rear band.
Notice how the spring retainer is flared in that first pic?
That is because the servo traveled to far instead of engaging the band like it should, it pushed the servo out so far that it pushed the retainer out.
There are two reasons this can happen.
1. A way out of adjustment rear band servo
2. A broken strut assembly.

That peice of metal looks like the end off of the strut assembly, and there could very well be another one like it that didn't fall down yet.

All of that stuff can be replaced with the trans in the car except for the band by removing the tail housing and pulling that pin at the top of the pic to the upper right of the band.
 

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And if that's the case, I believe the tailshaft needs to come off to get that rear pin out. Might be able to remove the bolts & rotate the housing. Not sure on that.
 
80fbody said:
And if that's the case, I believe the tailshaft needs to come off to get that rear pin out. Might be able to remove the bolts & rotate the housing. Not sure on that.
Click to expand...

Just the output shaft housing.
This picture is from a 4x4 but it's still the same idea.
This little spot of the extension housing holds the pin in the case.
 

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Randy sells his servos on ebay, it's easier to purchase them that way if you are an overseas buyer. His servo also comes with the thicker retainer, which is a nice feature.
 
Chrysler/Dodge pulled out of Australia in the early 80s and most of the good trans guys have sinced retirered so this forum is my biggest help.

Thanks AIV for the photos and link to the rebuild thread.

Also want to thank Trail Beast for the info on the strut assembly and removal of extension housing.

Pompis thanks for the link to Mr Randy, I have sent him an email so I hope he can help out since I'm in OZ.

Cheers
Karl
 
Take about a quick reply. Randy has already contacted me, he also confrimed that the piece in the pan looks to be the reverse band strut assembly, he also has offered more help.

Thanks
Karl
 
In your second picture, the band adjusting lock nut and screw are backed off. My guess is it was out of adjustment and the piston came out too far blowing the retainer past the snap ring.
 
MR4V said:
Chrysler/Dodge pulled out of Australia in the early 80s and most of the good trans guys have sinced retirered so this forum is my biggest help.

Thanks AIV for the photos and link to the rebuild thread.

Also want to thank Trail Beast for the info on the strut assembly and removal of extension housing.

Pompis thanks for the link to Mr Randy, I have sent him an email so I hope he can help out since I'm in OZ.

Cheers
Karl
Click to expand...

Bakerlite wrote that it may be easier buying from him at ebay so here is the link to Mr Randy's ebay site also.

http://www.ebay.com/sch/mrrandyj/m.html?_nkw=&_armrs=1&_ipg=&_from=
 
Thanks for the site info.
Randy is very helpful, I emailed him direct and he is now packing and send all the items required.

Thanks
 
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